1. Field of the Invention
This invention relates generally to the monitoring of the product quality of chlorine. More particularly, this invention relates to a system and method for monitoring chlorine for the presence of various contaminants.
2. Background
The demand for purer chlorine products is generally increasing. Industrial chlorine users need to produce higher quality products derived from chlorine in order to meet increasingly stringent safety and environmental standards, as well as to improve manufacturing operations. For example, contaminants in chlorine such as non-condensable gases including oxygen, nitrogen and carbon dioxide are undesirable because they generate unwanted chemical waste which is costly to dispose of. These contaminants, which may remain in the excess chlorine from a chemical process, tend to deplete the scrubber through which the excess chlorine is passed for disposal, as well as form other compounds which must be disposed of. Bromine in chlorine contaminates the products made from chlorine, and decreases the reactivity of intermediates made from chlorine, thereby effecting the manufacture of the final product.
Additionally, public chlorine users such as municipalities need purer chlorine for water treatment to reduce the costs involved in the removal of carcinogenic materials such as halomethanes. Potable waters, which are normally disinfected with chlorine, must meet imposed standards on contaminants such as chloroform and carbon tetrachloride.
Due to the demand for purer chlorine by its users, chlorine manufactures are being increasingly compelled to monitor the various contaminants in chlorine during the manufacturing process to ensure that the chlorine being produced meets the demand for purity and to be able to take rapid corrective measures to reduce and/or eliminate the contaminants when they begin to appear. Particular contaminants which may be present in the produced chlorine and which are desired to be eliminated, or at least greatly reduced, include bromine, non-condensable gases such as oxygen, nitrogen and carbon dioxide, and halocarbons, including methylene chloride, chloroform and carbon tetrachloride. In order to monitor the contaminants and have the ability to take corrective action, it is necessary that a suitable system and method be available which will accurately detect and measure such contaminants and which can be used on-line at the production site and take samples directly from the process stream.